DESCRIPTION: Goal-seeking appetitive behavior characterizes motivation. Despite its importance in systems from basic biological desires to complex achievement drives, the developmental origins of appetitive behavior are poorly understood. Recent studies of the development of feeding and drinking in rodents have shown that the oral reflexes for licking, lapping and swallowing are present from birth. These consummatory responses are under physiological control shortly thereafter. Dehydration, in particular, is a potent stimulus for intake of oral infusions in neonates. Nonetheless, new findings from the principal investigator's lab suggest that for at least one basic appetite, the drinking stimulated by cellular dehydration, goal-seeking appetitive behavior is only acquired by post-weaning experience in which the appetitive response is linked to physiological state. Appetitive components of other motives may similarly depend on specific learning experiences. The experiments of this proposal take advantage of the relatively well understood fluid balance and drinking system as a model with which to examine the emergence of the appetitive components of motivated behavior. The critical events for the acquisition of cellular-dehydration-induced drinking will be determined and the emergence of this appetitive response will be compared to the appetitive response for extracellular dehydration. Then the stimulus control of early appetitive responding will be examined and the nature of the acquired behavioral response explored. These experiments will guide a further initial analysis of the contribution of learning to the appetitive responses for feeding behavior. As a whole, this series of experiments should reveal the conditions for the acquisition of simple appetites, evaluate processes underlying this learning, and explore the ubiquity of the acquisition of appetitive components of motivated behavior.